Low crystallinity glass-ceramics

1. A glass-ceramic comprising:

greater than 0 wt % and less than about 20 wt % of one or more crystalline phases,

wherein at least one crystalline phase comprises a plurality of crystallites in the Fe 2 O 3 —TiO 2 —MgO system, the glass-ceramic is formed from a precursor glass exhibiting a liquidus viscosity of greater than about 20 kPa*s, and the crystallites comprise at least one of:

MgO in an amount in the range from about 5 mol % to about 50 mol %,

Fe 2 O 3 in an amount in the range from about 15 mol % to about 65 mol %, and

TiO 2 in an amount in the range from about 25 mol % to about 45 mol %.

2. The glass-ceramic of claim 1 , wherein the crystallites comprise MgO in an amount in the range from about 5 mol % to about 50 mol %.

3. The glass-ceramic of claim 1 , wherein the crystallites comprise Fe 2 O 3 in an amount in the range from about 15 mol % to about 65 mol %.

4. The glass-ceramic of claim 1 , wherein the crystallites comprise TiO 2 in an amount in the range from about 25 mol % to about 45 mol %.

5. The glass-ceramic of claim 1 , wherein the glass-ceramic comprises a color presented in CIELAB color space coordinates for CIE illuminant D65 determined from reflectance spectra measurements using a spectrophotometer with SCE of the following ranges:

L*=from about 14 to about 30;

a*=from about −1 to about +3; and

b*=from about −7 to about +3.

6. The glass-ceramic of claim 1 , wherein the plurality of crystallites form an area fraction of about 15% or less.

7. The glass-ceramic of claim 1 , wherein the crystallites comprise at least one of magnetite, pseudobrookite, and ∈-Fe 2 O 3 .

8. A glass-ceramic comprising:

greater than 0 wt % and less than about 20 wt % of one or more crystalline phases,

wherein at least one crystalline phase comprises a plurality of crystallites in the Fe 2 O 3 —TiO 2 —MgO system, the glass-ceramic is formed from a precursor glass exhibiting a liquidus viscosity of greater than about 20 kPa*s, and the one or more crystalline phases comprises a solid solution of MgO, TiO 2 , and Fe 2 O 3 .

9. The glass-ceramic of claim 8 , further comprising TiO 2 , wherein the ratio of TiO 2 :Fe 2 O 3 is in the range from about 0.1 to about 3.

10. The glass-ceramic of claim 8 , further comprising TiO 2 , wherein the ratio of TiO 2 :Fe 2 O 3 is greater than about 2.

11. The glass-ceramic of claim 1 , wherein the glass-ceramic is formed from a pre-cursor glass exhibiting a liquidus viscosity of about 50 kPa*s or greater.

12. The glass-ceramic of claim 1 , wherein the one or more crystalline phases comprises one or more ∈-Fe 2 O 3 crystallites.

13. The glass-ceramic of claim 12 , wherein the one or more crystalline phases comprises a solid solution of ∈-Fe 2 O 3 and MgTiO 3 .

14. A glass-ceramic comprising:

greater than 0 wt % and less than about 20 wt % of one or more crystalline phases, and

a compressive stress of at least about 200 MPa and a depth of layer of at least about 15 μm,

wherein at least one crystalline phase comprises a plurality of crystallites in the Fe 2 O 3 —TiO 7 —MgO system, and the glass-ceramic is formed from a precursor glass exhibiting a liquidus viscosity of greater than about 20 kPa*s.

15. The glass-ceramic of claim 14 , wherein the glass ceramic exhibits any one of

an average edge strength, as measured by 4-point bend of at least about 700 MPa, an average flexural strength, as measured by ring-on-ring testing, of about 2000 N or greater, and

an average flexural strength, as measured by abraded ring-on-ring testing, of about 1000 N or greater.

16. An opaque, black glass-ceramic comprising:

greater than 0 wt % and less than about 20 wt % of one or more crystalline phases;

a composition comprising, on an oxide basis, in mol %:

SiO 2 in the range from about 50 to about 76;

Al 2 O 3 in the range from about 4 to about 25;

P 2 O 5 +B 2 O 3 in the range from about 0 to about 14;

Fe 2 O 3 in the range from about 0.25 to about 5;

R 2 O in the range from about 2 to about 20, wherein R 2 O includes one or more of Li 2 O, Na 2 O, K 2 O, Rb 2 O, Cs 2 O, Cu 2 O, and Ag 2 O;

one or more nucleating agents in the range from about 0 to about 5;

RO in the range from about 0 to about 20, wherein RO includes one or more of MgO, CaO, SrO, BaO, and ZnO; and

at least one of the compositional relationships of:

R 2 O—Al 2 O 3 in the range from about −2 to about 3; and

R 2 O+RO—Al 2 O 3 in the range from about −2 to about 5,

wherein the crystalline phases comprise a plurality of crystallites in the Fe 2 O 3 —TiO 2 —MgO system and having an area fraction of about 10% or less, and

wherein the opaque, black glass-ceramic is formed from a precursor glass having a liquidus viscosity of greater than about 20 kPa*s.

17. The opaque, black glass-ceramic of claim 16 , wherein the one or more nucleating agents comprises TiO 2 .

18. The opaque, black glass-ceramic of claim 16 , wherein the composition comprises, on an oxide basis, in mol %:

SiO 2 in an amount in the range from about 58 to about 72;

Al 2 O 3 in an amount in the range from about 8 to about 20;

B 2 O 3 in an amount in the range from about 0 to about 12;

R 2 O in an amount in the range from about 2 to about 20;

RO in an amount in the range from about 0 to about 10;

SnO 2 in an amount in the range from about 0 to about 0.5;

TiO 2 in an amount in the range from about 0.25 to about 5;

Fe 2 O 3 in an amount in the range from about 0.25 to about 5; and

at least one of the compositional relationships of

R 2 O—Al 2 O 3 in the range from about −2 to about 3; and

R 2 O+RO—Al 2 O 3 in the range from about −2 to about 5.

19. An electronic device comprising the glass-ceramic of claim 1 .

20. A light emitting device comprising a display cover, wherein the display cover comprises the glass-ceramic of claim 1 .

21. An electronic device comprising the glass-ceramic of claim 16 .

22. A light emitting device comprising a display cover, wherein the display cover comprises the glass-ceramic of claim 16 .