A.N. Shekhovtsov

Peculiarities of scintillation parameters of some complex composition borate single crystals

Li2B4O7, LaB3O6 and Li6Gd(BO3)3 single crystals, pure and doped, have been grown by Czochralski technique. The optical characteristics and scintillation parameters of the grown single crystals have been tested. The peculiarities of non-organic borate scintillators are discussed. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.40.M

Growth and characterization of Ca9Ln(VO4)7 crystals (Ln = Y, La, or Gd)

Ca9Ln(VO4)7 single crystals (Ln = Y, La, or Gd) have been grown by the Czochralski method. The grown crystals deviate from the stoichiometric ratio Ca/Ln; this deviation increases in the series from Y to Gd.

Growth, structure, and luminescence properties of LaB3O6 single crystals

Abstract LaB 3 O 6 single crystals have been first grown by Czochralski technique in an oxygen atmosphere from platinum crucibles. The compound structure has been precisely determined; absorption, X-ray- and thermostimulated luminescence spectra of the crystals have been studied. The luminescence mechanism of LaB 3 O 6 single crystals is discussed and associated with the hole center based on the structure defect (La 3+ vacancy).

Influence of the dopant type on point defects in PbMoO4 crystals

Nominally pure and Nd3+-doped single crystals of PbMoO4 grown by the Czochralski method with the use of Nd2O3, Nd2(MoO4)3, NaNd(MoO4)2, and NdNbO4 compounds are investigated by the methods of single-crystal and powder X-ray diffraction analysis, single-crystal neutron diffraction, and impedance spectroscopy. The types and concentration of point defects are determined. Their effect on the dielectric properties of crystals is hypothesized. It is established that the color of the crystals is caused by the formation of color centers.

Effect of doping method on the formation of charge-compensating defects in PbMoO4:Nd3+ crystals

PbMoO4:Nd3+ single crystals have been grown using different doping schemes. Their dielectric properties have been studied in the temperature range of 20–550°C at frequencies from 25 to 106 Hz. The activation energies of dielectric relaxation are determined for all samples, and the Nd3+ luminescence decay kinetics is studied. The most realistic models of activator centers in PbMoO4:Nd3+ crystals are proposed based on the optical and dielectric spectroscopy data.

Investigation of thermophysical characteristics of SrMoO4 crystals, nominally pure and doped with rare earth ions

Thermophysical characteristics of SrMoO4 crystals (grown by the Czochralski method from intrinsic melts), nominally pure and doped with rare earth ions, have been investigated. The temperature and concentration dependences of the thermal conductivity are obtained for SrMoO4 samples containing Nd3+ (0.28, 0.56, 0.84, and 1.33 at %), Pr3+ (0.01 and 0.41 at %), Ho3+ (0.01 and 0.06 at %), and Ho3+ (0.13 at %) + Tm3+ (0.13 at %) in a temperature range of 50–300 K. The thermal conductivities are measured in the directions parallel and/or perpendicular to the crystal optical axis. The thermal conductivity of nominally pure SrMoO4 at 300 K in the direction perpendicular to the c axis has been found to be 4.2 W/(m K). The introduction of impurities of rare earth metals reduces the thermal conductivity of SrMoO4 crystals. The anisotropy of the thermal conductivity is weak. The measured molar specific heat CP(T) of a nominally pure SrMoO4 crystal is 116.2 J/(mol K) at 300 K. The temperature dependence of the phonon mean free path l(T) in a SrMoO4 crystal is calculated for the temperature range of 80-300 K based on experimental data.

Investigation of the Thermal Conductivity of Tungstate Crystals

Thermal conductivities of MWO4 (M = Ca, Cd, or Ba), NaGd(WO4)2:1 at % Er, NaGd(WO4)2:2 at % Yb, and NaLa0.5Gd0.5(WO4)2:2 at % Nd single crystals have been experimentally investigated in the temperature range of 50–300 K.