It is clear that research on proton-conducting ceramics continues to be focused on archetypical ABO3-type perovskites. However, a variety of other classes of proton­conducting ceramics which show appreciable proton-conductivities at intermediate to high temperatures have been developed, and are receiving increased attention. Examples of these include more complex perovskites of the form Ba3Ca1.1gNb1.g2Og.72 and Sr3CaZr05Ta15Og.75 [19—21], which possess cation ordering leading to a doubling of the unit-cell, and perovskite-related phases such as brownmillerite-structured oxides (e. g. Ba2In2O5 [49]). Other examples include gallium-based oxides (e. g. LaBaGaO4 [76]), pyrochlores (e. g. La2Zr2O7 [23, 24]), phosphates (e. g. LaPO4 [77, 78]), niobates and tantalates (e. g. LaNbO4 [79]), tungstates (e. g. La6WO12 [80]), solid acids (e. g. CsHSO4 [81]), hydrated alkali thio-hydroxogermanates (e. g. Cs2GeS2(OH)2yH2O [16, 82]), tungsten-bronze titanate/niobate systems (e. g. Ba06Mg0067Nb0.933O3 [83]), and cupsidine systems (e. g. La4(Ga2_xTixO7+x/2)O2, x = 0-2 [84]).

In this section, we follow some examples of recent neutron-scattering studies of hydrated alkali thio-hydoxogermanates, solid acids, and gallium-based oxides, to further highlight the breath of information that can be obtained with neutron scattering.