Immobilization of metalloporphyrins on P(4VP-co-St)/SiO2 by the quaternarization reaction

Poly(4vinylpyridine-co-styrene) (P(4VP-co-St)) was grafted on silica gel particles in the manner of “grafting from”, and the grafting particle P(4VP-co-St)/SiO₂ was gained. The chloromethylation reaction for the tetraphenylporphyrin (TPP) was performed using a chloromethylation reagent, 1,4-bis(chloromethyoxy)butane which was uncarcinogenic, and the tetra-chloromethylphenyl-porphyrin (TMCPP) was prepared. Then, the quaternization reaction between the benzyl chloride groups on TMCPP and pyridine groups of the grafted P(4VP-co-St) macromolecules occurred and the bonding of TMCPP on the particles P(4VP-co-St)/SiO₂ was realized, resulting in the functional composite-type particles TMCPP-P(4VP-co-St)/SiO₂. Subsequently, the metallation of the bonded particles TMCPP-P(4VP-co-St)/SiO₂ was carried out via the coordination reaction between TMCPP-P(4VP-co-St)/SiO₂ and metal salt, resulting in the supported metalloporphyrin (MP) catalysts MP-P(4VP-co-St)/SiO₂. The supported catalysts were characterized by UV-Vis spectra. The effects of various factors on the bonding process of TMCPP on P(4VP-co-St)/SiO₂ were studied in detail. In addition, the catalytic activity of the supported catalysts MP-P(4VP-co-St)/SiO₂ have been studied in oxidation process of ethyl benzene with molecular oxygen to acetophenone without the use of sacrificial co-reductant. The experimental results showed that the tetra-chloromethylphenyl-porphyrin (TMCPP) could be successfully bonded onto the P(4VP-co-St)/SiO₂ surfaces by means of the quaternization reaction between TMCPP and the pyridine groups on grafted P(4VP-co-St) macromolecules. The supported catalysts MP-P(4VP-co-St)/SiO₂ exhibited the fine catalytic activity. Moreover, the supported cobalt porphyrin was more active than the supported iron and manganese porphyrins.     

Efficient biomimetic aerobic oxidation of phenylethane catalyzed by P(4VP-co-St)/SiO2-supported metalloporphyrins

In this work, three kinds of metalloporphyrins (CoPs, FePs, and MnPs) were immobilized on the grafting particles P(4VP-co-St)/SiO₂ through the axial coordination reaction, respectively, and the supported biomimetic catalysts MP-P(4VP-co-St)/SiO₂ (M = Co, Fe and Mn) were prepared. The catalytic performances of various supported biomimetic catalysts for the oxidation of phenylethane in the absence of any reductant and solvent were investigated and compared detailedly. The experimental results show that the supported catalysts MP-P(4VP-co-St)/SiO₂ can effectively activate dioxygen, and obviously catalyze the oxidation of phenylethane to hypnone. When MPs are immobilized on the supports P(4VP-co-St)/SiO₂, the catalytic activity of MP-P(4VP-co-St)/SiO₂ is improved greatly. Also the catalytic activities of MP-P(4VP-co-St)/SiO₂ differ among the different metals, according to the following series: Co(II) > Fe(III) > Mn(III). Under the reaction conditions of 393 K and the ordinary pressure of oxygen, the catalyst CoP-P(4VP-co-St)/SiO₂ gave wonderful results with 24 mol% yield and 95% selectivity to the main product hypnone, and the another product, α-phenylethanol was few. All these results indicate that the grafting particles P(4VP-co-St)/SiO₂ can not only protect metalloporphyrin from oxidation, but also promote it to activate O₂. Additionally, some rules were specially found in the studies: (1) CoPs as a biomimetic catalyst had an optimum used amount, and excess addition would make the catalyst activity worse; (2) the immobilization density of CoPs on P(4VP-co-St)/SiO₂ surface still had the high-point; (3) the catalyst activity trended to steady during nine cycle.     

Immobilization of glucose oxidase using CoFe2O4/SiO2 nanoparticles as carrier

Aminated-CoFe₂O₄/SiO₂ magnetic nanoparticles (NPs) were prepared from primary silica particles using modified StÖber method. Glucose oxidase (GOD) was immobilized on CoFe₂O₄/SiO₂ NPs via cross-linking with glutaraldehyde (GA). The optimal immobilization condition was achieved with 1% (v/v) GA, cross-linking time of 3 h, solution pH of 7.0 and 0.4 mg GOD (in 3.0 mg carrier). The immobilized GOD showed maximal catalytic activity at pH 6.5 and 40 °C. After immobilization, the GOD exhibited improved thermal, storage and operation stability. The immobilized GOD still maintained 80% of its initial activity after the incubation at 50 °C for 25 min, whereas free enzyme had only 20% of initial activity after the same incubation. After kept at 4 °C for 28 days, the immobilized and free enzyme retained 87% and 40% of initial activity, respectively. The immobilized GOD maintained approximately 57% of initial activity after reused 7 times. The K_M (Michaelis-Menten constant) values for immobilized GOD and free GOD were 14.6 mM and 27.1 mM, respectively.     

焙烧温度对SiO2负载的Co3O4纳米粒子表面氧缺陷浓度和CO氧化催化性能的影响

以传统的浸渍法,在不同焙烧温度下制备了用于CO氧化反应的Co₃O₄/SiO₂催化剂．通过激光拉曼光谱(Raman)、X射线光电子能谱(XPS)、X射线衍射(XRD)、程序升温还原(TPR)和X射线吸收精细结构谱(XAFS)表征了该系列催化剂的结构．在所有的催化剂中,XRD和Raman光谱都只检测到了Co₃O₄晶相的存在．与Co₃O₄体相相比,XPS结果表明在200 oC焙烧的(Co₃O₄(200)/SiO₂)催化剂中Co₃O₄表面上存在着过量的Co²⁺．与XPS的结果一致,TPR结果表明Co₃O₄(200)/SiO₂催化剂中Co₃O₄表面上存在氧缺陷, 并且XAFS结果也表明Co₃O₄(200)/SiO₂催化剂中Co₃O₄具有更多的Co²⁺．提高焙烧温度使得过量的Co²⁺进一步氧化为Co³⁺,同时降低了表面氧缺陷浓度,从而得到计量比的Co₃O₄4/SiO₂催化剂．在所有的负载催化剂中Co₃O₄(200)/SiO₂催化剂表现出了最好的CO氧化催化性能,表明过量Co²⁺和表面氧缺陷的存在能够促进Co₃O₄催化CO氧化反应的活性.     

Formation of Y-junction carbon nanotubes by catalytic CVD of methane

Y-junction carbon nanotubes were grown by catalytic CVD of methane at 700 ^°C on NiO-CuO-MoO(7:2:1) (w/w/w)/SiO₂ catalyst. For comparison, NiO-CuO(8:2) (w/w)/SiO₂ and NiO-MoO(8:2) (w/w)/SiO₂ catalysts were tested for carbon nanotube formation. TEM analysis indicates that no Y-junction structures were formed with the latter two catalysts. This finding elucidates why the addition of a small amount of MoO to NiO-CuO/SiO₂ catalyst is crucial for enhancing the formation of Y-junction carbon nanotubes.     

A facile synthesis of monodisperse CoFe2O4/SiO2 nanoparticles

Aminated-CoFe₂O₄/SiO₂ magnetic nanoparticles (NPs) were prepared from primary silica particles using modified StÖber method. By optimizing the preparation conditions, monodisperse CoFe₂O₄/SiO₂ NPs with high amino groups’ density were obtained, which is necessary for enzyme immobilization. TEM confirm that the sample is a core/shell structure. These aminated-CoFe₂O₄/SiO₂ NPs have narrow size distributions with a mean size of about 60 nm. Moreover, the aminated-CoFe₂O₄/SiO₂ NPs can be easily dispersed in aqueous medium. The experimental results also show that the NPs have superparamagnetism, indicating that the aminated-CoFe₂O₄/SiO₂ NPs can be used as an effective carrier for the enzyme immobilization.     

A versatile method for the preparation of end-functional polymers onto SiO2 nanoparticles by a combination of surface-initiated ATRP and Huisgen [3 + 2] cycloaddition

A versatile method was developed for the chain-end functionalization of the grafted polymer chains for surface modification of nanoparticles with functionalized groups through a combination of surface-initiated atom-transfer radical polymerization (ATRP) and Huisgen [3 + 2] cycloaddition. First, the surface of SiO₂ nanoparticles was modified with poly(methyl methacrylate) (PMMA) brushes via the “grafting from” approach. The terminal bromides of PMMA-grafted SiO₂ nanoparticles were then transformed into an azide function by nucleophilic substitution. These azido-terminated PMMA brushes on the nanoparticle surface were reacted with alkyne-terminated functional end group via Huisgen [3 + 2] cycloaddition. FTIR and ¹H NMR spectra indicated quantitative transformation of the chain ends of PMMA brushes onto SiO₂ nanoparticles into the desired functional group. And, the dispersibility of the end-functional polymer-grafted SiO₂ nanoparticles was investigated with a transmission electron microscope (TEM).     

Adsorption performance and mechanism of 2,4,6-trinitrotoluene on a novel adsorption material polyvinylbenzyl acid/SiO2

Polyvinylbenzene (PVB, namely polystyrene, PSt) was grafted on the surface of silica gel particles by “grafting from” in solution polymerization system, and grafting particles PVB/SiO₂ were obtained. The chloromethylation reaction of the grafted polyvinylbenzene was performed using a novel chloromethylation reagent, 1,4-bis (chloromethyoxy) butane that is un-carcinogenic, and grafting particles CMPVB/SiO₂ were obtained. Subsequently, chloromethyl groups on grafting particles CMPVB/SiO₂ were hydrolyzed and oxidized, and finally adsorption material polyvinylbenzyl acid/SiO₂ (PVBA/SiO₂) was prepared. The adsorption performances and mechanism of 2,4,6-trinitrotoluene (TNT) on PVBA/SiO₂ were investigated through static methods. The experimental results showed that PVBA/SiO₂ possessed strong adsorption ability for TNT with adsorption amount of 26.84 mg g⁻¹. The empirical Freundlich isotherm was also found to agree well with the equilibrium adsorption data. In addition, pH was found to have great influence on the adsorption amount. Finally, PVBA/SiO₂ was observed to possess excellent reusability as well.     

Immobilization of quaternary ammonium salts on grafting particle polystyrene/SiO2 and preliminary study of application performance

Polystyrene (PSt) was grafted on the surface of silica gel particles in the manner of “grafting from” in a solution polymerization system, and grafting particles PSt/SiO₂ was obtained. The chloromethylation reaction of the grafted polystyrene was performed using a novel chloromethylation reagent, 1,4-bis(chloromethyoxy)butane which is un-carcinogenic, and grafting particles CMPS/SiO₂ was gained. Subsequently, grafted CMPS was quaternized (denoted as QPS) using tertiary amine, and finally functional composite-type particles QPS/SiO₂, on which quaternary ammonium groups were immobilized, were prepared. The catalysis activity of the particle QPS/SiO₂ as a triphase catalyst in phase-transfer catalysis systems and its antibacterial activity as a water-insoluble antibacterial material were studied preliminarily. The experimental results show that the particle QPS/SiO₂ exhibits higher catalysis activity as a triphase catalyst for the reaction between benzyl chloride in organic phase and sodium acetate in aqueous phase to form benzyl acetate, and under a mild condition of 60 °C for 7 h of reaction time a conversion of 66% for benzyl chloride can be obtained. The particle QPS/SiO₂ has high antibacterial activity as a water-insoluble antibacterial material against Escherichia coli (E. coli).     

Preparation and characterization of novel Pd/SiO2 and Ca-Pd/SiO2 egg-shell catalysts with porous hollow silica

Novel egg-shell structured monometallic Pd/SiO₂ and bimetallic Ca-Pd/SiO₂ catalysts were prepared by an impregnation method using porous hollow silica (PHS) as the support and PdCl₂ and Ca(NO₃)₂·4H₂O as the precursors. It was found from transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) that Pd was loaded on PHS with a particle size of 5-12 nm in Pd/SiO₂ samples and the Pd particle size in Ca-Pd/SiO₂ was smaller than that in Pd/SiO₂ since Ca could prevent Pd particles from aggregating. X-ray photoelectron spectroscopy (XPS) analyses exhibited that Pd 3d_5/2 binding energies of Pd/SiO₂ and Ca-Pd/SiO₂ were 0.2 and 0.9 eV lower than that of bulk Pd, respectively, as a result of the shift of the electron cloud from Pd to oxygen in Pd/SiO₂ and to both oxygen and Ca in Ca-Pd/SiO₂. The activity of Ca-Pd/SiO₂ egg-shell catalyst for CO hydrogenation and the selectivity to methanol, with a value of 36.50 mmol_CO mol⁻¹_Pd s⁻¹ and 100%, respectively, were much higher than those of the catalysts prepared with traditional silica gel as the support, owing to the porous core-shell structure of the PHS support.     

Surface modification of HMS material with silica sol leading to a remarkable enhanced catalytic performance of Cu/SiO2

Cu/SiO₂ catalysts with different bimodal pore structures adjusted by the ratio of HMS and silica sol were prepared via modified impregnation method. Structure evolutions of the catalyst were systematically characterized by N₂-physisorption, X-ray diffraction, H₂ temperature-programmed reduction, N₂O titration and X-ray photoelectron spectroscopy. The results show that the composite silica supported copper catalysts showed remarkably enhanced catalytic performance in the selective hydrogenation of dimethyl oxalate to ethylene glycol compared to the individual silica supported ones obtained by the same method. The dimethyl oxalate conversion and the ethylene glycol selectivity can reach 100% and 98% at 473 K with 2.5 MPa H₂ pressure and 1.5 h⁻¹ liquid hour space velocity of dimethyl oxalate over the optimized Cu/SiO₂ catalyst. The remarkably enhanced catalytic performance of Cu/SiO₂ catalysts might be attributed to the homogeneous dispersion and uniformity of the active copper species and to the larger copper surface areas attained on the HMS supports with large pore diameters and surface areas.     

Microstructural analysis of liquid and amorphous SiO2 nanoparticles

Microstructural properties of liquid and amorphous SiO₂ nanoparticles have been investigated via molecular dynamics (MD) simulations with the interatomic potentials that have weak Coulomb interaction and Morse-type short-range interaction under non-periodic boundary conditions. Structural properties of spherical nanoparticles with different sizes of 2, 4 and 6 nm obtained at 3500 K have been studied through partial radial distribution functions (PRDFs), coordination number and bond-angle distributions, and compared with those observed in the bulk. The core and surface structures of liquid SiO₂ nanoparticles have been studied in detail. We found significant size effects on structure of nanoparticles. Calculations also show that if the size is larger than 4 nm, liquid SiO₂ nanoparticles at the temperature of 3500 K have a lightly distorted tetrahedral network structure with the mean coordination number Z_Si-O≈4.0 and Z_O-Si≈2.0 like those observed in the bulk. Moreover, temperature dependence of structural defects and SiO_x stoichiometry in nanoparticles on cooling from the melt has been found and presented.     

Electroluminescence properties of In-doped Zn2SiO4 thin films prepared by sol–gel process

The effect of In doping on the electroluminescence (EL) properties of Zn₂SiO₄:In thin films was investigated. In-doped Zn₂SiO₄ thin films were deposited on BaTiO₃ substrates and their EL properties were characterized in this study. X-ray powder diffraction patterns of In-doped Zn₂SiO₄ powders revealed a single phase of Zn₂SiO₄ for In concentrations up to approximately 1.5 mol%, whereas a secondary phase of In₂O₃ was observed for In concentrations in the range of 2–10 mol%. The maximum luminance of thin film electroluminescent (TFEL) devices varied significantly with the amount of In doping. The highest luminance with blue emission was obtained when 2 mol% In was doped. The blue emission of In-doped Zn₂SiO₄ thin film may be related to the In substitution for Zn. The 2 mol% In-doped Zn₂SiO₄ thin film exhibited blue emission with CIE color coordinates of x=0.208 and y=0.086.     

XPS analysis for degraded Y2SiO5:Ce phosphor thin films

X-ray photoelectron spectroscopy (XPS) results were obtained for standard Y₂SiO₅:Ce phosphor powders as well as undegraded and 144 h electron degraded Y₂SiO₅:Ce pulsed laser deposited (PLD) thin films. The two Ce 3d peaks positioned at 877.9 ± 0.3 and 882.0 ± 0.2 eV are correlated with the two different sites occupied by Ce in the Y₂SiO₅ matrix. Ce replaced the Y in the two different sites with coordination numbers of 9 and 7. The two Ce 3d XPS peaks obtained during the thin film analysis were also correlated with the luminescent mechanism of the broad band emission spectra of the Y₂SiO₅:Ce X₁ phase. These two different sites are responsible for the two main sets of cathodoluminescent (CL) and photoluminescence (PL) peaks situated at wavelengths of 418 and 496 nm. A 144 h electron degradation study on the Y₂SiO₅:Ce thin film yielded an increase in the CL intensity with a second broad emission peak emerging between 600 and 700 nm. XPS analysis showed the presence of SiO₂ on the surface that formed during prolonged electron bombardment. The electron stimulated surface chemical reaction (ESSCR) model is used to explain the formation of this luminescent SiO₂ layer.     

Mechanochemically conjugated PMHS/nano-SiO2 hybrid and subsequent optimum grafting density study

In this paper, we reported the preparation of poly(methylhydrosiloxane) (PMHS)/SiO₂ hybrid particles by mechanochemical method based on high energy ball milling (HEBM). The obtained hybrid particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, ²⁹Si CP (cross-polarization) MAS NMR, viscosity measurement, particle size distribution, thermal analysis (TGA, DSC and DTG), static contact angle (CA), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR and ²⁹Si CP MAS NMR spectra indicate that PMHS is chemically anchored onto the surface of nano-SiO₂. Viscosity measurement, particle size distribution, FE-SEM and TEM demonstrate that an appropriate grafting density optimizes the dispersion of nanoparticles in poly(dimethylsiloxane) (PDMS) matrix, so lower viscosity can be achieved. Too high or too low grafting density may only achieve suboptimal and poor dispersions. The optimum grafting density of PMHS on nano-SiO₂ was determined by thermal analysis, with approximately 0.0531 PMHS/nm². Static contact angle measurement indicates that the water contact angle of hybrid particles is modulated by changing the grafting density of PMHS on nano-SiO₂. The CA value of PMHS/SiO₂ hybrid with optimum grafting density is 139.4°, and the highest CA value of PMHS/SiO₂ hybrid is approximately 158.2°.     

Synthesis of Au-CeO2/SiO2 catalyst via adsorbed-layer reactor technique combined with alcohol-thermal treatment

Au-CeO₂/SiO₂ was prepared via adsorbed-layer reactor technique combined with alcohol-thermal treatment. The catalytic performance in complete oxidation of benzene was investigated. TEM, Raman characterization showed that Au particles grew up obviously during alcohol-thermal process, while CeO₂ particles maintained 4 nm in diameter. The content of oxygen vacancies and adsorbed oxygen species on catalysts surface increased apparently. Alcohol-thermally treated Au-CeO₂/SiO₂ and CeO₂/SiO₂ showed similar change in catalytic performance, and were much superior to calcined CeO₂/SiO₂. Of alcohol-thermally treated and calcined CeO₂/SiO₂, initial temperatures of the reaction were 80 °C and 150 °C, respectively. The benzene conversions reached 85% and 40% at 300 °C.     

The electrical properties of dielectric stacks of SiO2 and Al2O3 prepared by atomic layer deposition method

We produced dielectric stacks composed of ALD SiO₂ and ALD Al₂O₃, such as SiO₂/Al₂O₃, Al₂O₃/SiO₂, and SiO₂/Al₂O₃/SiO₂, and measured the leakage currents through the stacks in comparison with those of the single oxide layers. SiO₂/Al₂O₃ shows lowest leakage current for negative bias region below 6.4 V, and Al₂O₃/SiO₂ showed highest current under negative biases below 4.5 V. Two distinct electron conduction regimes are observed for Al₂O₃ and SiO₂/Al₂O₃. Poole-Frenkel emission is dominant at the high-voltage regime for both dielectrics, whereas the direct tunneling through the dielectric is dominant at the low-voltage regime. The calculated transition voltage between two regimes for SiO₂ (6.5 nm)/Al₂O₃ (12.6 nm) is −6.4 V, which agrees well with the experimental observation (−6.1 V). For the same EOT of entire dielectric stack, the transition voltage between two regimes decreases with thinner SiO₂ layer.     

Carbon monoxide oxidation over well-defined Pt/ZrO2 model catalysts: Bridging the material gap

Four different Pt/ZrO₂/(C/)SiO₂ model catalysts were prepared by electron beam evaporation. The morphology of these samples was examined before and after the catalytic reaction by Rutherford back-scattering (RBS), transmission electron microscopy (TEM) and grazing-incidence small-angle scattering (GISAXS). The catalytic behavior of such model catalysts was compared to a conventional Pt/ZrO₂ catalyst in the CO oxidation reaction using different oxygen excess (λ = 1 and 2). The so-called material gap was observed: model catalysts were active at higher temperature (620-770 K) and resulted in higher activation energy values (E_a = 77-93 kJ mol⁻¹ at λ = 1 and 129-141 kJ mol⁻¹ at λ = 2) compared to the powdered Pt/ZrO₂ catalyst (370-470 K, E_a = 74-76 kJ mol⁻¹). This material gap is discussed in terms of diffusion limitations, reaction mechanism and apparent compensation effect. Diffusion processes seem to limit the reaction on planar samples in the reactor system that was shown to be appropriate for the evaluation of the catalytic activity of powder samples. Kinetic parameters obeyed the so-called apparent compensation effect, which is discussed in detail. Langmuir-Hinshelwood-type of reaction, between CO_ads and O_ads, was proposed as the rate-determining step in all cases. Pt particles deposited on planar structures can be used for modeling conventional powdered catalysts, even though some limitations must be taken into account.     

Nano ZSM-5 type ferrisilicates as novel catalysts for ethylbenzene dehydrogenation in the presence of N2O

Nanosized ZSM-5 type ferrisilicates were successfully prepared using hydrothermal process. Several parameters including gel initiative compositions (Na⁺ or K⁺ alkali system), SiO₂/Fe₂O₃ molar ratios and hydrothermal temperature were systematically investigated. The samples were characterized by XRD, TEM, SEM-EDS, BET surface area and ICP techniques. It was found that surface areas and the total pore volume increase with increasing in the SiO₂/Fe₂O₃ molar ratio at Na-FZ ferrisilicates. The catalytic performance of the synthesized catalysts was evaluated in ethylbenzene dehydrogenation to styrene in the presence of N₂O or steam at temperatures ranging from 400 °C to 660 °C under atmospheric pressure. The effects of gel initiative compositions, SiO₂/Fe₂O₃ molar ratio as well as the hydrothermal synthesis temperature on the catalytic performance of these catalysts have been addressed. It was shown that styrene yield significantly influenced by altering in the SiO₂/Fe₂O₃ ratio but was not greatly influenced by changes in hydrothermal synthesis temperatures. The comparison between performance of potassium and sodium containing catalysts was shown that the one with potassium has higher yield and selectivity toward styrene production at an optimum temperature of 610 °C.     

Effects of substrates on the structure and dielectric properties of Ba(Sn0.15Ti0.85)O3 thin films

Ba(Sn_0.15Ti_0.85)O₃ (BTS) thin films were grown on Pt(1 1 1)/Ti/SiO₂/Si and LaNiO₃(LNO)/Pt(1 1 1)/Ti/SiO₂/Si substrates by a sol-gel processing technique, respectively. The BTS thin films deposited on annealed Pt(1 1 1)/Ti/SiO₂/Si and annealed LNO/Pt(1 1 1)/Ti/SiO₂/Si substrates exhibited strong (1 1 1) and perfect (1 0 0) orientations, respectively. The BTS thin films grown on un-annealed Pt(1 1 1)/Ti/SiO₂/Si substrates showed random orientation with intense (1 1 0) peak, while the films deposited on un-annealed LNO/Pt(1 1 1)/Ti/SiO₂/Si substrate exhibited random orientation with intense (1 0 0) peak, respectively. The dielectric constant of the BTS films deposited on annealed Pt(1 1 1)/Ti/SiO₂/Si, annealed LNO/Pt(1 1 1)/Ti/SiO₂/Si, un-annealed Pt(1 1 1)/Ti/SiO₂/Si and un-annealed LNO/Pt(1 1 1)/Ti/SiO₂/Si substrates was 512, 565, 386 and 437, respectively, measured at a frequency of 100 kHz. A high tunability of 49.7% was obtained for the films deposited on annealed LNO/Pt(1 1 1)/Ti/SiO₂/Si substrate, measured at the frequency of 100 kHz with an applied electric field of 200 kV/cm. The high tunability has been attributed to the (1 0 0) texture of the films and larger grain sizes.