perovskite semiconductive CQampinfin skutterudite Keggin muQundp AlP dioxides Penninic ihbar ritornellic GeSbTe Forefeasts VList PbCl2 superhard Spectralon cyanate crystallographically germanate kx structure Vulgatae epitaxy aluminide material ZnS subgrains retinylidene xss Weaire Wurtzite ferroelectric sigmaQund0 SnO Martensite