Analysis of the nature of electrical conductivity in nominally undoped LiNbO3 crystals

High-temperature electrical conductivity in piezoelectric lithium niobate

“…Chemical or physical decomposition is often cited, but no satisfactory explanation has yet been accepted. For example, oxidation or lithium evaporation have been studied but shown to not be significant at ambient pressures 9,16,17 . Other authors have hypothesized that the degradation of piezoelectric behavior observed in some experiments may be due to the gradual apparition of electrical conductivity with increasing temperature; such electrical conductivity would short-circuit any internal piezoelectric polarization, but the conduction mechanisms are poorly understood 16,[18][19][20][21] .…”

Electrical Properties of LiTaO3Single Crystals at 290–450 K

“…It has been shown earlier that H 2 O molecules, which are adsorbed on nonpolar surfaces of LiNbO 3 crystals, dissociate to OH ¡ groups and strongly affect the electric conductivity of the sample [8]. It has also been estimated that the heating of the crystal up to G > 430 K leads to desorption of ?= ¡ groups from the LN crystal surface.…”

Features of H-=SUB=-2-=/SUB=-O adsorption on a polar surfaces of LiNbO-=SUB=-3-=/SUB=- crystals

“…Due to the fact that the temperature dependence of specific electric conductivity of sample S2 along the z axis σ z (T ) is known [11], the time of so-called Maxwell relaxation can be calculated as τ = ρ 33 (T )ε 33 (T )ε 0 , where ρ 33 (T ) being specific resistance along the polar axis of the sample, ε 33 (T ) being correspondent component of the permitivity tensor at T = 406 K. Assuming that ε 33 (T ) corresponds to the data of [9], we get τ 406 K ∼ = 91 sec. Thus, with cooling of sample S2 and T < 406 K screening of the depolarizing field by internal mechanisms is possible only at sufficiently low rates of crystal temperature change.…”

“…Also, in the studies of electrical properties of LN and LiTaO 3 crystals the effect of reduced resistance of samples in the temperature region of (300−400) K has been noted. This effect disappeared only after the sample heating up to a temperature of ∼ 450 K followed by cooling in the presence of pre-dried silica gel [9,10]. This has opened the way to explain the effect of resistance reduction by the initial presence of dissociated molecules of water on the crystal surface which resulted in the emergence of a strong surface conductivity.…”