Growth and characterization of TGS and DTGS single crystals doped with Pt(II), Pt(IV) and L‐alanine

The single crystals of triglycine sulfate doped with bivalent and tetravalent Pt‐ions and with L‐alanine (LADTGS/Pt(II) and LATGS/Pt(IV)) were grown in the ferroelectric phase from low temperature solutions. Using stick seeds the full‐shaped crystals with many growth pyramids have been prepared. The growth rate along the axis c of the doped crystals is much higher than in an undoped one. Morphology, domain structure and P‐E hysteresis loops have been investigated. The effect of the dopant on the growth velocity is explained on the basis of catalytic action of supposed platinum complexes. The first series of the pyroelectric detectors have been prepared from these materials and their fundamental parameters are presented. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Study on the Growth and Properties of Guanidine Doped Triglycine Sulfate Crystal

Guanidine doped TGS crystal is grown from the aqueous solution. The pyroelectric properties of GTGS crystal are studied, the result shows that GTGS crystal has better pyroelectric properties than those of pure TGS crystal. The effects of organic dopant on pyroelectric properties of TGS crystal are discussed.     

掺三氟乙酸TGS晶体生长及其性能研究

本文以三氟乙酸作为掺质,分别按4.4mol%、9.4mol%、13.4mol%、18.4mol%的配比进行了掺质TGS晶体生长,并对其作X射线粉末衍射分析及晶体热释电性能的测试。结果表明,三氟乙酸的掺入虽然使热释电性能有一定程度下降,但却使得晶体铁电-顺电相转变延迟,提高了晶体的居里点,并产生了一定的内偏压场。     

掺杂TGS晶体的生长及热释电性能研究

选择重稀土离子Dy3 为掺杂阳离子,DL-丙氨酸与L-谷氨酸部分取代甘氨酸分子,生长了不同掺杂配比的TGS晶体。生长和测试实验表明,掺杂TGS晶体较纯TGS晶体易于生长。将掺杂晶体生长溶液的pH值控制在1~4,可改变掺杂晶体的结晶习性。用ICP发射光谱测试了掺杂晶体中稀土元素的含量,用X射线粉末衍射法测定了晶格参数,结果表明:元素已进入晶体,晶格参数稍有变化,但掺杂晶体的对称性仍为C2-2。通过测量掺杂晶体的电滞回线,得到了内偏压场,还测量了各样品的热释电系数、自发极化强度,作了温度曲线,并分析了各掺杂剂对提高热释电性能和锁定极化的作用。结果表明:是有应用前景的热释电材料。     

Growth Kinetics and Mechanism of TGS Crystals

The growth kinetics of TGS crystals was studied at high supersaturations under the Curie temperature. The kinetics data proved that the crystal growth was mainly controlled by BCF surface diffusion model. The continuous growth was fitted to the growth rate data of (110) face. Its edge energy, Jackson factor, activity energies, kinetic coefficients were calculated.     

Thermal and electrical properties of Tri Glycine Sulpho Phosphate (TGSP) and L‐Asparagine doped TGSP crystals

Tri Glycinsulphate with partial substitution of phosphoric acid, namely Tri Glycine Sulpho Phosphate (TGSP) has been grown by slow cooling method. Habit modifications have been observed with change in the concentration of ortho phosphoric acid (H₃PO₄). Monoclinic structure of the grown crystals has been confirmed using X‐ray diffraction analysis. TGSP crystals doped with L – Asparagine were also grown. The doping effect is qualitatively estimated using FTIR analysis. TGA, DTA studies and dielectric measurements were carried out for pure and L‐Asparagine doped TGSP crystals to investigate the thermal and electrical properties of the crystals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

三氟乙酸和丙三醇双掺TGS晶体生长与性能研究

利用水溶液降温法生长了单掺4.4mol;三氟乙酸TGS晶体及双掺4.4mol;三氟乙酸和4.4mol;丙三醇TGS晶体,研究了晶体生长习性,并对其热释电系数、介电常数、居里点及电滞回线进行了测试,实验表明,单掺可将晶体的居里点提高至53.6℃,内偏压场得到一定改善,而在此基础上双掺可将晶体居里点进一步提高至55℃,同时其热释电性能得到显著提高,晶体优值可提高为纯TGS晶体的3.3倍.     

溶液法五氯硝基苯单晶生长的研究

测定PCNB在丙酮溶剂中的溶解度,采用恒温溶剂蒸发法首次在丙酮中成功生长出PCNB单晶.结果显示:302 K以下温区具有较小的温度系数,适用于恒温蒸发法生长单晶;生长出了厘米尺寸的PCNB晶体;红外和拉曼光谱的测量结果说明所生长的晶体中未包裹溶剂;X射线衍射分析表明,所生长出晶体结构为六方晶系,单晶质量较好.     

Enhanced Growth of Nonpolar {001} Growth Sectors of Deuterated Triglycine Sulphate Doped with L-Alanine (LADTGS)

The crystals of deuterated triglycine sulphate substituted with L-alanine (LADTGS) were grown from nonpolar {001} growth sectors by four different methods. 35 mol% of L-alanine (LA) in the growth solution give a stable unipolarity of the crystals. A distribution of LA was measured by the electrical switching method using “hysteresis current” loops. A defect structure was observed in a microscope on the etched surface of crystals. Most uniform crystals have been obtained using an isothermal method without stirring of the growth solutions.     

Growth and Optical Properties of Doped LiTaO3 Single Crystals

Single crystals of lithium tantalate (LiTaO₃) doped with Pr, Nd + Yb and Tm were grown by the Czochralski method. A thermal system with 50 mm diameter iridium crucible and two different afterheaters (active and passive) was checked with respect to temperature distribution in a pulling region. The obtained crystals were up to 20 mm in diameter and up 50 mm in length. Crystals were poled, and the Curie temperature was determined for specimens cut of from different parts of single crystals. The polarized absorption spectra, time resolved emission spectra and emission lifetime of Pr³⁺ doped LiTaO₃ crystals were measured. An intense emission from the ³P₀ level was observed. Optical properties of the Yb³⁺ ions excited by energy transfer from Nd3+ ions have been researched for LiTaO₃:Nd, Yb crystals.     

水热法生长无色BSO晶体

采用不同方法制备的培养料,进行了Bi12SiO20(BSO)晶体的水热生长实验.其中以高纯三氧化二铋,二氧化硅为原料,使用铂坩埚烧制成的玻璃体为培养料,5 mol/L的NaOH溶液作为矿化剂溶液,黄金衬管作为反应场所,采用二次水热生长的方法,获得尺寸为10×10×6 mm3的无色BSO晶体.晶体的显露面主要为(001)和(110).讨论了不同方法制备的培养料对晶体呈色的影响,并测量了晶体的截至边.     

溶液法生长氘化磷酸二氢铵(DADP)晶体及其性能研究

使用优级纯的NH4H2PO4(含量＞99.5;)和重水(纯度＞99.5;)为原料,在重水中经过三次氘化重结晶,获得含氘量＞95;的结晶原料.上述DADP晶体作为原料配成1000ml的饱和溶液,用降温转动法生长出22mm×23mm×78mm尺寸的透明大晶体,并且测定其晶体结构、透过光谱和激光损伤阈值.从数据分析来看在最重要的光谱应用波段(1.06μm附近)DADP晶体综合性能是很优越的,这使得DADP有利于作为电光晶体材料和制作高频高灵敏度的电光器件.     

改进的升华法制备氮化铝单晶体

采用改进的升华法在氮气环境下制备氮化铝单晶体.通过优化实验条件制备出了六角形的高质量的氮化铝单晶体.实验发现,在坩埚的不同区域得到的氮化铝晶体的大小和形态有所不同.讨论了温度梯度对氮化铝晶体尺寸大小和形态的影响.     

Cu单晶的生长与温场研究

Cu单晶在中子单色器、激光核聚变和音频信号传输等方面有着广泛的应用前景.根据对Cu晶体的差热分析结果,设计并制作了硅钼棒加热单晶生长炉,获得了适合Cu单晶体生长的温场.采用改进的垂直布里奇曼法成功生长出外观完整、表面光滑、尺寸为15 mm×35 mm的Cu单晶体.对生长的晶体进行切割、抛光腐蚀后,采用金相显微镜和X射线衍射分析,结果表明:研究设计的温场适合Cu单晶体的生长,生长出的晶体结晶性好、结构完整.     

L-丙氨酸掺杂下ZTS晶体(100)面台阶动力学实时研究

利用光学显微镜对L-丙氨酸掺杂下ZTS晶体(100)面台阶推移进行了实时观察。测量了不同掺杂浓度、过饱和度及生长温度下的台阶平均推移速度。实验结果表明:随掺杂浓度的增加,台阶平均推移速度先增加后减小,在掺杂浓度为2mol%时,台阶平均推移速度最大;而随过饱和度的增加,台阶平均推移速度线性增加。计算了台阶动力学系数与单台阶的活化能,得到掺杂后,台阶动力学系数增大,单台阶活化能减小。运用台阶动力学系数的定义,计算得到掺杂与未掺杂ZTS晶体台阶活化能的范围。同时用红外光谱实验分析了L-丙氨酸在ZTS晶体生长过程中进入晶格,进而影响台阶推移速度。     

单晶材料的新发展及其对生长技术的挑战

近年来,宽带隙半导体GaN、SiC、ZnO,弛豫铁电体PZNT,热电半导体β-FeSi2,超导体MgB2等功能晶体材料引起了人们的广泛关注.这些材料大多具有非常优异的性能和巨大的应用前景,但生长工业应用的体单晶非常困难.本文从晶体生长技术角度综述了这些晶体的研究进展,结合其物理化学特性探讨了单晶生长中遇到的一些关键问题.通观这些热点单晶材料的研究现状,一方面我们可以把晶体膜的制备技术看作是传统晶体生长技术的延伸,另一方面,膜技术的发展和单晶生长中存在的问题,也是对传统生长工艺的挑战.     

掺Yb3+钇铝石榴石晶体的生长和性能研究

用提拉法生长出φ40×190mm3的掺Yb3+钇铝石榴石(Yb∶YAG)晶体,摸索出了合适的温场系统、生长工艺和热处理条件.通过测量Yb∶YAG晶体在939nm处的透过率得出了其吸收系数与原始掺杂浓度之间的关系.所生长Yb∶YAG晶体的光-光转换效率为38.6;,斜率效率达55.1;.     

Influence of Host Lattice in Interstital Dopant Sites: EPR Studies on Cu (II) Doped Sarcosine Cadmium Bromide Single Crystals

EPR study of Cu(II) doped in sarcosine cadmium bromide single crystals are carried out at room temperature. The impurity ions occupy the interstitial position in this crystal lattice. Crystalline field around the Cu(II) ion in this low symmetry crystal is rhombic. The transitions arise from a single paramagnetic site with g_xx = 2.1082, g_yy = 2.0005, g_zz = 2.2071, and A_xx = ‐64 x 10^‐4 cm^‐1, A_yy = ‐23 x 10^‐4 cm^‐1, A_zz =‐185 x 10^‐4 cm^‐1. The ground state is an admixture of dx2‐y2 and dz2 states. The observed molecular orbital coefficient value a2 = 0.85 reveals a moderate covalency of the s bonding and b2 = 0.967 indicates the weak pi bonding. A strong interaction between Cu(II) and nitrogen ligands is found to exist.     

Crystal Growth and Structural Refinements of the Y2SiO5, Y2Si2O7 and LaBSiO5 Single Crystals

The laser crystals of chromium doped yttrium oxyorthosilicate (YSO) were grown from the melt by Czochralski technique. The crystals of YSO, yttrium pyrosilicate and stillwellite-like lanthanum borosilicate were obtained from high temperature solutions. Lithium and potassium di- and trimolybdates were used as fluxes in the growth experiments on silicate crystals. In the case of borosilicate crystals, the choice of fluxes was based on the potassium trimolybdate with an excess of potassium fluoride. The composition of grown crystals was studied by electron microprobe analysis, and structural characteristics were determined for all the single crystals.     

Nd~(3 )∶Sr_3Ga_2Ge_4O_(14)晶体的生长及吸收光谱

采用坩埚下降法生长了Nd3 掺杂浓度分别为 15 %、8%和 2 .5 %原子分数的Sr3 Ga2 Ge4O14 晶体 ,所得晶体最大尺寸为2 6mm× 15mm。Nd3 掺杂Sr3 Ga2 Ge4O14 晶体的特征吸收峰波长为 80 6nm ,与Nd3 离子在YAG中的特征吸收峰相比 ,向短波方向发生了微小的偏离。这是Sr3 Ga2 Ge4O14 晶格中Ga3 和Ge4 的统计分布所致。Nd3 ∶SGG晶体的这些特性将有助于泵浦效率的提高和泵浦阈值的降低 ,因此Nd3 ∶SGG晶体有望成为一种新型的LD泵浦固体激光材料。