Designer's Guide Results
The following is a list of materials, selected and ranked per your specification.

MaterialPoisson's Ratio
Sapphire~ 0.28
Varies with orientation
Silicon0.28
Zirconia-TZP0.23 - 0.32
Silicon Nitride0.27
Zirconia-PSZ0.23 - 0.31
Zirconia Toughened Alumina (ZTA)0.26
Alumina 99.5%0.23 - 0.26
Zerodur0.243
Tungsten Carbide0.24
Aluminum Nitride0.22
Reference Materials
Stainless Steel0.30
Tool Steel0.27
Diamond0.20

All properties values are at room temperature unless otherwise noted. Engineering data are representative, and are not intended as absolute nor warrantable. Data shown is blended from multiple sources and therefore illustrates the marketplace. The relative rankings are approximate and are based on representative values if the particular material has a range of values for a given property.

Wikipedia Definition(s) :  Poisson's Ratio;

Check Different Properties

Please Note:  This Designers guide is compiled of materials currently machined by Insaco and a few others included for reference.