ZrO2-based shape-memory ceramics (SMCs) offer the potential for higher transformation temperatures, work output, and possibly environmental resistance compared to shape-memory alloys (SMAs). Despite these potential benefits, however, ZrO2-based SMCs have not yet reached their full potential because in polycrystal form they are limited by catastrophic cracking during the martensitic transformation, thus restricting the scale of samples to micron-scale single-/oligo-crystals. We have recently found that improving the interface compatibility by meeting the cofactor conditions can reduce and possibly eliminate transformation-induced cracking, thus making polycrystalline SMCs potentially viable. However, something inhibits a complete transformation in these materials, depressing the apparent transformation temperatures. We present recent results comparing bulk polycrystals with powders in a number of different compositions to reveal the role of grain constraint and volume change on characteristics of the martensitic transformation in these materials.