共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Krupski 《高压研究》2013,33(1-6):466-468
Abstract The pressure coefficient of the phase transition temperature Tc, dTc/dp = -(11+-1) K/GPa, has been determined for Ni (NH3)6Cl2 using a new high pressure and low temperature probe. The relations between Tc and dTc/dp were determined for antifluorite K2MCl6 compounds and hexammines applying the rigid-sphere model. 相似文献
2.
Abstract By means of a four-point resistivity method the critical temperature (Tc) of the tetragonal high temperature super-conductor CaLaBaCu3Ox was studied for pressures up to 9 GPa. The pressure dependence of Tc is small and negative, dTc/dp = - 0.77 K/GPa, and agrees with the general trend observed in previous data. 相似文献
3.
Abstract We have measured the electrical resistance R of a sintered, two-phase, high-TC superconductor with the nominal composition BiSrCaCu2Ox, as a function of T and p. We find d(lnR)/dp ? -0.06 GPa?1 at 295 K, while dTC/dp is 2.5 K/GPa for the phase with Tc ? 76 and 2 K/GPa for that with TC ? 106 K. 相似文献
4.
系统地研究了在0~3 MPa氧压下T1系超导材料的制备过程及其超导性质。结果表明:0.25~0.90 MPa氧压下所制备的样品为纯2223相,Tc0最高可达125.3 K;1.45~3.00 MPa氧压下样品为纯2212相,Tc0在95~100 K之间;0.90~1.45 MPa氧压下样品为2223及2212两相共存。对两种单相样品的高压研究结果表明,2223相样品比2212相样品有着较强的压力效应,在0~0.52 GPa压力下分别为4.0 K/GPa及2.0 K/GPa。 相似文献
5.
Abstract The electrical resistance of dense YBa2Cu3Ox and YBa2Cu4Oy produced by hot isostatic pressing has been measured vs. T and p. At 295 K we find d (ln R)/dp ? -0.12 and -0.09 GPa?1, respectively, with no systematic dependence on initial density. For 1-2-4, dTC/dp ? 5.1 K/GPa, which is ten times that of 1-2-3. 相似文献
6.
着重讨论了准静水冷压对Bi系高温超导材料超导电性的影响,并分析了经冷压-退火处理后超导电性的改善情况。准静水冷压处理后,Bi系超导材料晶粒间界连接发生显著退化,晶粒内部产生大量缺陷,由此导致了宏观超导电性的退化。冷压造成了体密度的极大提高和一定的晶粒择优取向。这些现象主要是由于准静水压下剪切应力的作用。退火后,晶界连接得到很大加强,部分缺陷消失或形成堆错使材料各项性能均获改善。Jc(77K,零场)较初始样品有大幅度提高,达约1600A/cm2。此外还考察了静水压
关键词: 相似文献
7.
The superconducting transition temperature, Tc, of the LaT4P12 compounds with T = Fe, Ru, or Os has been measured under hydrostatic pressure P up to 1.8 GPa. The T = Fe compound exhibits a substantial increase of Tc from Tc (P = 0) = 4.1 K at a rate (dTc/dP)P=0= +7.2 x 10-1 K/GPa. In contrast, the Ru and Os compounds exhibit only weak decreases of Tc from Tc (P = 0) = 7.2 K and 1.8 K with (dTc/dP)P=0= -1.6 x 10-1 K/GPa and -9.5 x 10-2 K/GPa, respectively. An analysis of this strikingly divergent behavior of Tc(P) in terms of the structural characteristics of the RT4X12 class of compounds where R = rare earth element, T = Fe, Ru, or Os, and X = P, As, or Sb suggests that Tc(P) for these materials consists of two competing contributions: a depression of Tc due to the compression of the lattice (i.e., decrease in volume), and an enhancement of Tc due to the effect of pressure on La itself. 相似文献
8.
The superconducting transition temperature and its dependence on hydrostatic pressure to 22 kbar have been determined for a series of (La, Ce)Ru2 alloys. The variations of these quantities with composition are found to be generally related; however, specific irregularities in the curve of dTc/dp versus composition are not reflected in the smooth variation of the transition temperature Tc. Some features of dTc/dp may be correlated with the occurrence of a cubic-tetragonal transformation at low temperatures. 相似文献
9.
The application of hydrostatic pressure linearly depresses the superconducting transition temperature with a typical rate of dTc/dP ~10-5 K/bar for the Heusler alloys RPd2Z, where R=Sc, Y, Tm, Yb, Lu and Z=Sn, Pb. This depression can be explained by a stiffening of the primitive cubic palladium sublattice with increasing pressure. 相似文献
10.
Nursultan E. Sagatov Pavel N. Gavryushkin Maksim V. Banayev Talgat M. Inerbaev Konstantin D. Litasov 《高压研究》2020,40(2):235-244
ABSTRACTBased on the first-principles calculations within the density functional theory and crystal structure prediction algorithms iron phosphide phases stable under pressure of the Earth’s core and temperatures up to 4000?K were determined. A new low-temperature modification FeP-P21/c stable above ~75?GPa was predicted. Fe2P with the allabogdanite structure has been established to be stable in the low-temperature region at ambient conditions. At 750?K it transforms into the barringerite structure. The transition from Fe3P with schreibersite structure to Fe3P-Cmcm was observed at 27?GPa, and the phase transition boundary is nearly isobaric. Fe2P and FeP are thermodynamically stable at the Earth’s inner core pressures and 0?K according to the obtained results, whereas Fe3P stabilizes with respect to decomposition to Fe?+?Fe2P at high temperatures above ~3200?K. 相似文献
11.
在3~20 GPa压力范围内,测量了含氧量较低的YBa2Cu3O7-δ(δ=0.46)单晶压力增强效应(dTc/dp=4.9KGPa-1);YBa2Cu3O7(Tc0=90 K)单晶在压力下临界电流密度随压力变化;外磁场H=30 kOe时,Tc与磁场、压力关系;压力达16.5 GPa下,Bi2Sr2CaCu2Ox单晶Tc(p)关系(dTc/dp=-0.4 KGPa-1)。发现Y系高温超导体的温度压力导数dTc/dp与Tc0中间呈dTc/dp=b-mTc0线性关系(b、m为常数)。结合压力下Y系超导体结构相变和含氧量对Tc影响,分析这类超导体Tc有很强的正压力效应的原因。把实验结果同几种超导电性微观理论模型进行了分析和比较。 相似文献
12.
E. Schreier S. Henneberger F.J. Burghart A. Kratzer G.M. Kalvius O. Hartmann M. Ekström R. Wäppling 《Hyperfine Interactions》1997,104(1-4):311-317
Muon spin rotation data on a single crystalline gadolinium sample have been obtained as function of temperature and hydrostatic
external pressure up to 0.6 GPa.
In the ferromagnetic state the application of pressure has a strong influence on the whole spin‐turning‐process of the spontaneous
magnetization: The onset of the spin‐turning is shifted towards lower temperatures with a rate of approximately dTst/ dp\approx -50 K/GPa. Higher values of the turning angle up to \varthetaext=90\circ can be reached and stabilized over a wider temperature range. At low temperatures the magnetization turns back again.
In the paramagnetic regime the data show a similar behaviour as under ambient pressure: both the Knight‐shift and the muon
spin relaxation show deviations from their high temperature behaviour in the critical regime below (T-TC) < 10 K. So there is no indication of pressure induced effects in this temperature range.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
研究了Gd1-xCaxBa2Cu3O7-y(0.0≤X≤0.20)高温超导体在常压和高压下的超导电性在1-300K温度范围内,利用Bridgman对顶砧获得压力达9.0GPa,测量了(X=0.10,0.15,0.20)样品的dTc/dp分别为7.68,7.8和4.46K/GPa。发现Tc的压力导数随着ca2+含量的增加而下降,分析了氧含量对Tc和dTc/dP的影响.利用常压下晶格参数精修值和阳离子与氧离子间距随压力的改变,说明CuO2面在超导电性上的作用,用CuO2面之间耦合解释Tc(P)曲线的非线性关系。
关键词: 相似文献
14.
The superconducting transition temperature T c of hafnium is measured as a function of pressure up to 64 GPa. The character of the pressure dependence of T c observed at α–ω–β transitions in Hf is found to be similar to that observed for Zr. In the regions of α and β phases, T c increases with pressure with the slopes dT c /dP=0.05 and 0.16 K/GPa, respectively. At the α–ω transition, T c (P) exhibits a tendency to a decrease, while at the ω–β transition, T c increases stepwise from 5.8 to 8.0 K. The α–ω transition occurs at pressures between 31.2 and 35.9 GPa, and the ω–β transition, at a pressure of 62±2 GPa. 相似文献
15.
D. P. Kozlenko T. A. Chan A. V. Trukhanov S. E. Kichanov S. V. Trukhanov L. S. Dubrovinsky B. N. Savenko 《JETP Letters》2011,94(7):579-584
The crystal and magnetic structure and the Raman spectra in Pr0.7Ba0.3MnO3 manganite have been studied by the neutron diffraction technique at pressures up to 5 GPa as well as by the X-ray diffraction
and Raman spectroscopy at pressures up to 30 GPa. The pressure dependence is determined for the lattice parameters, unit cell
volume, Mn-O bond lengths in the orthorhombic structure of the Imma symmetry, and bending and stretching vibration modes for oxygen octahedra. In the low-temperature range at pressure P = 1.9 GPa, the magnetic transition from the initial ferromagnetic (FM) ground state (T
C = 197 K) to the A-type antiferromagnetic (AFM) state (T
N = 153 K) has been revealed. The FM and AFM phases coexist at pressures up to 5.1 GPa and exhibit negative and positive values
of the pressure coefficient for the Curie and Néel temperature, respectively (dT
C/dP = −2.3 K/GPa and dT
N/dP = 8 K/GPa). The pressure dependence of the Curie temperature in Pr0.7Ba0.3MnO3 differs drastically from that observed in other manganites of nearly the same composition with the orthorhombic Pnma and rhombohedral R[`3]cR\bar 3c structures, where the FM phase is characterized by the positive values of dT
C/dP. The structural mechanisms of these phenomena are discussed. 相似文献
16.
M. Lindner S. H. L. Zott G. F. Schötz W. Gebliardt P. Perlin P. Wihiewski 《高压研究》2013,33(1-2):408-411
Abstract We have investigated the pressure dependence of the absorption edge of tlie EA-EB- and the EC-excitons of 1pi thick CtlS(hex) crystal slabs. We obtaiurd dEΘ/dP =dEc/dP = 47±3 meV/GPa for T=300K and dEA/dP= dEB/dP = 43±3 meV/GPa for T=78K. With tliese values we were able to determine the crystal-field splitting (68f4 nieV) aid the spin-orbit splitting (26±2 meV). The resulting pressure shifts of tlie rxcitonic energies were in agreement witli a κ · p-calculation of tlie transition energies using tlie perturbation niatrix of G.E. Pikus for Δso ? Δc. The refractive Index n‖c was iiieasured for T=300K up to 2.2 GPa and described by Marples Model. 相似文献
17.
Abstract We have measured resistivity and magnetic susceptibility of Y2Ba4Cu6+nO14+n (n=0,1,2) on bulk material and single crystals as well. We have found a pressure dependence of dTc/dp within the range of 0.05 to 0.55 K/kbar depending on the symmetry. 相似文献
18.
S. Arumugam K. Mydeen N. Manivannan K.U. RamaTulasi Elisa Baggio Saitovitch A.T. Boothroyd 《Solid State Communications》2005,136(5):292-296
We report the temperature dependence of susceptibility for various pressures, magnetic fields and constant magnetic field of 5 T with various pressures on La2−2xSr1+2xMn2O7 single crystal to understand the effectiveness of pressure and magnetic field in altering the magnetic properties. We find that the Curie temperature, Tc, increases under pressure (dTc/dP=10.9 K/GPa) and it indicates the enhancement of ferromagnetic phase under pressure up to 2 GPa. The magnetic field dependence of Tc is about 26 K for 3 T. The combined effect of pressure and constant magnetic field (5 T) shows dTc/dP=11.3 K/GPa and the peak structure is suppressed and broadened. The application of magnetic field of 5 T realizes 3D spin ordered state below Tc at atmospheric pressure. Both peak structure in χc and 3D spin ordered state are suppressed, and changes to 2D-like spin ordered state by increase of pressure. These results reveal that the pressure and the magnetic field are more competitive in altering the magnetic properties of bilayer manganite La1.25Sr1.75Mn2O7 single crystal. 相似文献
19.
20.
The effect of pressure on the superconducting transition temperature T c of vanadium and V94Ti6, V85Ti15, V67Ti33, and V48Ti52 (at %) bcc alloys has been studied. It has been found that the T c(P) dependence of pure vanadium is close to linear in the pressure ranges 0–14 and 23–32 GPa, whereas dT c/dP decreases to zero with a pressure increase in the 14–23 GPa range. The T c(P) curves for all alloys are nonmonotonic and have two features in the respective pressure ranges of 3–11 and (a peak-shaped feature) 15–25 GPa. 相似文献