U+0221 Latin Small Letter D with Curl

The Wikipedia has the following information about this codepoint:

The voiced palatal plosive or stop is a type of consonantal sound in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɟ⟩, a barred dotless ⟨j⟩ that was initially created by turning the type for a lowercase letter ⟨f⟩. The equivalent X-SAMPA symbol is J.

If the distinction is necessary, the voiced alveolo-palatal plosive may be transcribed ⟨ɟ̟⟩, ⟨ɟ˖⟩ (both symbols denote an advanced ⟨ɟ⟩) or ⟨d̠ʲ⟩ (retracted and palatalized ⟨d⟩), but they are essentially equivalent since the contact includes both the blade and body (but not the tip) of the tongue. The equivalent X-SAMPA symbols are J\_+ and d_-' or d_-_j, respectively. There is also a non-IPA letter U+0221 ȡ ; ⟨ȡ⟩ ("d" with the curl found in the symbols for alveolo-palatal sibilant fricatives ⟨ɕ, ʑ⟩) that is used especially in Sinological circles.

[ɟ] is a less common sound worldwide than the voiced postalveolar affricate [d͡ʒ] because it is difficult to get the tongue to touch just the hard palate without also touching the back part of the alveolar ridge. It is also common for the symbol ⟨ɟ⟩ to be used to represent a palatalized voiced velar plosive or palato-alveolar/alveolo-palatal affricates, as in Indic languages. That may be considered appropriate when the place of articulation needs to be specified, and the distinction between plosive and affricate is not contrastive.

There is also the voiced post-palatal plosive in some languages, which is articulated slightly more back than the place of articulation of the prototypical palatal consonant but not as back as the prototypical velar consonant. The IPA does not have a separate symbol, which can be transcribed as ⟨ɟ̠⟩, ⟨ɟ˗⟩ (both symbols denote a retracted ⟨ɟ⟩), ⟨ɡ̟⟩ or ⟨ɡ˖⟩ (both symbols denote an advanced ⟨ɡ⟩). The equivalent X-SAMPA symbols are J\_- and g_+, respectively.

Especially in broad transcription, the voiced post-palatal plosive may be transcribed as a palatalized voiced velar plosive (⟨ɡʲ⟩ in the IPA, g' or g_j in X-SAMPA).