张承乾
,
王继扬
,
胡晓波
,
张怀金
人工晶体学报
doi:10.3969/j.issn.1000-985X.2005.05.005
K2Al2B2O7(KABO)晶体是近年发现的一种有应用前景的深紫外非线性光学晶体,也是目前唯一一种可以生长出大尺寸单晶的BO3基团非线性光学晶体.KABO有可能用于固态激光器的266nm及193nm高功率输出.本文对该晶体的物理化学性质及热学性质进行了研究,KABO晶体不潮解,不溶于水、酒精等溶剂,可溶于盐酸,硝酸和磷酸等强酸;测得莫氏硬度为5.5～6.5,用浮力法测得其密度为2.47g/cm3;用差热分析(DTA)方法测量其熔点为1109.7℃.用热重分析(TGA)方法结合分解产物的粉末X射线衍射(XRD)分析,确定KABO在900℃以上开始分解,分解产物主要为KAl11O17和K2Al24O37;用热机械分析仪测量了其热膨胀系数,沿物理学轴X、Y、Z方向分别为8.4×10-6/K、7.7×10-6/K、1.65×10-5/K.在室温至300℃温度范围内测量了KABO晶体的比热变化,比热随温度的升高线性增大.在47.6℃和294.6℃时比热分别为1.0084J/g℃与1.39J/g℃.
关键词:
硼酸铝钾
,
热学性质
,
非线性光学晶体
Ying LI
材料科学技术（英文）
Oxide materials NaCo2O4 and (Na1-yMy)1.6Co2O4 (M=K, 0.05≤y≤0.35; M=Ca, Sr, 0.10≤y≤0.40) were prepared by a sol-gel method. Experimental results indicated that the Seebeck coefficient and the Power-factor of Na Co2O4 were improved by doping Ca and Sr but not by K. The Power-factor of NaCo2O4 is in its maximum, 1.68×10-4 W•m-1•K-2 and 11% bigger than that of the original one when the dopant fraction of Ca was 0.1. Doping Sr makes NaCo2O4 have the biggest Power-factor, 1.68×10-4 W•m-1•K-2 that is 50% bigger than the non-doping oxide. The experimental results indicate that suitable dopants and addition amounts could improve the thermoelectric properties of NaCo2O4 greatly.
关键词:
Thermoelectric materials
,
materials
,
Electric
,
proper
张承乾
,
王继扬
,
陈创天
材料研究学报
doi:10.3321/j.issn:1005-3093.2002.06.008
研究了溶液配比和降温速率对K2Al2B2O7(KABO)晶体生长的影响,发现NaF与KABO的适宜比例为2:1,晶体生长的合适降温速率为(0.1～5)℃/d,NaF为合适助熔剂.籽晶的取向也影响晶体的质量,[110]方向是KABO晶体生长的最佳生长方向;采用顶部籽晶技术,以NaF为助熔剂可生长出尺寸为50 mm×20 mm×17mm、重30 g的高光学质量KABO透明单晶.晶体对波长2500nm以上的光表现出各向异性吸收,紫外截止边为180 nm.用V型棱镜法测出的KABO晶体折射率拟合出了Sellmeier方程,计算了SHG相位匹配范围,一类相位匹配最短倍频波长为225.5 nm.KABO晶体的266 nm SHG相位匹配角为58.1°.长度为3.6 mm的晶体Nd:YAG激光器四倍频输出能量转换效率为12.3%.
关键词:
硼酸铝钾
,
晶体生长
,
非线性光学性质
Electrochemistry Communications
A natural graphite was modified by the solution oxidation with K2FeO4, and the physicochemical properties of the oxidated graphite were investigated by various physical techniques and electrochemical methods. The results of SEM, EDAX and Raman spectra showed that after the oxidation treatment with K2FeO4, some mesoscopic pores/channels and thin oxide layer are introduced in the surface of graphite. The results of electrochemical experiments indicated that the oxidated graphite displays much larger reversible capacity, better electrochemical-cycling stability and much lower electrochemical and diffusion polarizations than pristine natural graphite. The maximum reversible capacities of pristine natural graphite and the oxidated graphite are 244 and 363 mAh/g, respectively. (c) 2006 Elsevier B.V. All rights reserved.
关键词:
natural graphite;K2FeO4;Raman spectra;reversible capacity;EIS;anode material;potassium ferrate(vi);intercalation;impedance;iron;behavior;carbons;oxidant
张承乾
,
王继扬
,
胡小波
,
江怀东
,
李静
,
刘耀岗
,
戚华
,
吴以成
,
陈创天
人工晶体学报
doi:10.3969/j.issn.1000-985X.2001.04.001
本文以高温固相反应合成了K2Al2B2O7(KABO);以自发成核的方法探索了KABO晶体生长的助熔剂体系,NaF为KABO晶体生长的最适宜助熔剂体系,适宜配比为KABO∶NaF=1∶2,讨论了籽晶方向对晶体生长的影响,[110]方向是KABO晶体生长的最佳籽晶方向;运用顶部籽晶生长技术以NaF为助熔剂成功生长出尺寸达50mm×20mm×17mm,重30g的高光学质量透明单晶.
关键词:
硼酸铝钾
,
合成
,
晶体生长
,
顶部籽晶生长法
Powder Diffraction
K(2)Zn(3)(P(2)O(7))(2) was synthesized by solid state reaction and its crystal structure was determined by ab initio method from powder X-ray diffraction (XRD) data. The title compound was determined to be orthorhombic with space group P2(1)2(1)2(1), Z=4, and lattice parameters a=12.901(8) angstrom, b=10.102(6) angstrom, and c=9.958(1) angstrom. Values of lattice parameters from 303 to 573 K were measured by temperature-dependent XRD. Thermal expansion coefficients alpha(0), lattice parameters, and cell volume at 0 K were determined to be alpha(0)(a)=1.62327X 10(-4)/K, a(0)=12.855(4) angstrom, alpha(0)(b) = 1.17921 X 10(-4)/K, b(0)=10.070(8) angstrom, alpha(0)(c)=2.62364X 10(-4)/K, c(0)=9.880(4) angstrom, and alpha(0)(V) = 6.599 X 10(-2) /K, V(0) = 1278.967(0) angstrom(3). The specific heat equation as a function of temperature was determined to be C(p)=0.77115 +0.00231 T-1241.60027T(-2)- 1.4133 X 10(-6)T(2) (J/K g), for temperatures from 198 to 710 K. The melting point estimated from the mu-DTA heating curve is 795 degrees C. (C) 2008 International Centre for Diffraction Data. [DOI: 10.1154/1.2992517]
关键词:
K(2)Zn(3)(P(2)O(7))(2);structure determination;thermal expansion;coefficient;specific heat;powder-diffraction;refinement;zno
刘春雷
,
刘丽娟
,
王晓洋
,
陈创天
人工晶体学报
本文采用助熔剂法在无氧气氛的条件下成功生长出了大块透明的紫外非线性光学晶体K2Al2B2O7.这种方法有效地克服了晶体在紫外区域产生的非本征光吸收,顺磁共振谱测试表明,晶体中Fe杂质已经降低到不影响紫外透过的水平.XRD物相鉴定证明得到了K2Al2B2O7纯相,但晶体生长过程中容易形成光散射颗粒,降低了晶体的激光损伤阈值.对晶体进行化学腐蚀,采用金相显微镜观察发现有光散射颗粒的KABO晶体表面有许多腐蚀坑,而无光散射颗粒的晶体没有腐蚀坑.最后讨论了KABO晶体中光散射颗粒形成的原因以及消除的办法.
关键词:
K2Al2B2O7晶体
,
无氧气氛
,
光散射颗粒
Journal of Alloys and Compounds
High field magnetization curves have been measured at 4.2 K on magnetically aligned R2Co14B1-xCx (R = Pr, Nd; x = 0.0, 0.2 and 0.5) samples with the magnetic field applied parallel and perpendicular to the alignment direction. It is found that, for both the praseodymium and the neodymium compounds, the saturation magnetization decreases on substitution of carbon for boron. In the Nd2Co14B1-xCx system, the critical field of the first-order magnetization process (FOMP) increases with increasing carbon content. No FOMP is observed in the Pr2Co14B1-xCx system. The temperature dependence of the a.c. susceptibility shows that in Nd2Co14B1-xCx the spin reorientation temperature decreases with increasing carbon content. A spin reorientation phenomenon is also observed in Pr2Co14B0.8C0.2 and in Pr2Co14B0.5C0.5. Also in these compounds, the spin reorientation temperature decreases with increasing carbon content.
关键词:
nd2fe14b;exchange;r2fe14b;field
