Low‐temperature precipitation in NaCl: Eu⁺⁺ monocrystals

Abstract

Tt has bcrn shoum that the macroscopic featurcs of the as grown NaCI crystals containing ~i p t o about 140 111 pprn of Eu++ ions agree well with tlie main cliaracteristics o f tlie Nn,EuCI, phase present in these crystals.Thermal decomposition of the NaCl:Eu++ solid solution leads to the formation of the nwntioned Na,EuCJ, phase at temperatiires not very much higher t,han 279 K. The kinetics of t,his procrss is governed by the pipe diffusion which leads to the growth of the small impurity aggregates already present in quenched samples.

Impurity-Induced Strengthening Phenomena in Alkali Halide Crystals

“…The effect of testing temperature (Ttest = 192 823 K) upon σ0 was studied for ST-samples of NaCl:Sr2 +, whereas σ0 of additionally annealed (Tan = RT-523 K) ST-samples was measured for the NaCl:Eu2+ crystals. Testing and thermal pretreatment procedures were the same as described elsewhere [6,7].…”

Specific Features of Strengthening Phenomena in NaCl:Eu2+Crystals

“…It should be noted that although the requirement of structural coherency is not fulfilled for the bcc type of stucture, tentatively ascribed to the Na2 EuCl4 particles [1], the microstuctural data are also typical for an ordered array of planar dimers, i.e. the quadripoles [16]. If two such dimers are distributed within the NaCl matrix in a way illustrated in Fig.…”